Abstract: The active probe power supply uses isolated voltage sensing which powers the active probe from a power supply which uses the system under test power supply in a reference. This power supply interconnection arrangement makes use of Schottky diodes to interconnect the power supply leads of both systems. These diodes turn on quickly to eliminate the potential damage when a shorting fault occurs in either the emulator or the system under test. Furthermore, these diodes behave as capacitors when the power supply voltages are equal to provide high frequency grounding and to maintain a common logic 1 level to provide maximum noise margin. These diodes also introduce a significant impedance in the power supply control loop thereby avoiding loop instability and timing variations due to load driving.